Memorex 102 20MB Hard disk - Found It!

[Tony Duell]

> A quick update:  The drive spins up, comes ready and is passing the seek 
> test in Morrow's FORMATHD.COM utility.  The header read fails on all 

Sinc this drive has a transparent cover, I assume you can see the heads 
moving during the seek trst.

> sectors and all cylinders, so something is still amiss.  I tried 
> re-writing the sector headers (if I interpret correctly, it is possible to 
> simply rewrite the headers without disturbing data in the sector proper - 

That is not unheard-of. Howeever,  I would be a little wary of writing to 
a drive that didn;t read correctly. If something is faulty, it's quite 
possible it's going to write somewhere it shouldn't. And since the drive 
fails on every sector, I would think the fualt is unlikely to be simply 
bad formatting data on the disk.

> a new one on me!) but that didn't help.  No error on write, but they 
> cannot be read back.

What error do you get if you try to read them? Does it manage to find 
anything?

> 
> I'll start poking around in the read logic next.  Getting closer, anyway.

I've not looked at the schematics, but I guess I'd start by seeing if (a) 
it was reading anything (do you get any sensible-looking pulses at the 
read data output -- and rmemeber that in 99% of drives the pusle width is 
irrelevant, it's set by a monostable on the logic board, it's the pulse 
spacing that defines the data), and (b) is it selecting one (and only 
one) head

-tony